Baddeleyite - Encyclopedia

    Class : Oxides and hydroxides
    Subclass : Oxides
    Crystal System : Monoclinic
    Chemistry : ZrO2
    Rarity : Rare

Baddeleyite is the natural oxide of zirconium. It is a rare mineral in rocks with a high silica deficit, from nepheline syenites and carbonatites to kimberlites and anorthosites. Baddeleyite is unalterable and is concentrated in alluvial deposits where it can constitute important placers. It owes its name to Joseph Baddeley who discovered it in 1890 at Kollonnagam in Sri Lanka. The crystals are rare and of varied habitus : slightly elongated tabular, stocky or elongated prismatic, rarely isometric. Baddeleyite is especially common in small fibroradiated or fibrous botryoidal masses, usually black in color, but which can present a wide range of colors (yellow, green, brown, colorless, etc.). Baddeleyite placers are one of the world's largest reserves of zirconium.

Main photo : Baddeleyite From Mount Somma, Naples, Italy © Chinellato Matteo

Baddeleyite from Poços de Caldas, Minas Gerais, Brazil © Christopher O'Neill
Baddeleyite in epitaxy on zirconolite from In Den Dellen, Germany © Volker Heck
Baddeleyite from Laacher See, Germany © Stephan Wolfsried
Baddeleyite from Case Collina, Tuscany, Italy © Christian Rewitzer

Baddeleyite in the World

The largest known crystals (6 cm) were extracted from the pegmatites of the nepheline syenites of Kovdor (Kola, Russia). The Poços de Caldas carbonatite (Minas Gerais, Brazil) contains an impressive quantity of thoriferous baddeleyite, essentially in the form of small botryoidal masses; its erosion feeds very important placers. Beautiful rolled crystals are also recovered from the gem-bearing alluviums of Ratnapura (Sri Lanka). Baddeleyite is also known in nepheline lava from Mount Somma (Italy).

Baddeleyite in France

In France, baddeleyite is reported in the mines of Costabonne (Pyrénées-Orientales).

Twinning and special crystallizations

Twins are ubiquitous in this species on {100} and {110}, both of which may be polysynthetic, however they are rarer on {201}.

Fakes and treatments

No fake or treatment identified for this mineral species.

Hardness : 6.5
Density : 5.4 to 6
Fracture : Irregular
Trace : White to brown

TP : Opaque to transparent
RI : 2.130 to 2.200
Birefringence : 0.070
Optical character : Biaxial -
Pleochroism : None
Fluorescence : None

Solubility : Insoluble

Magnetism : None
Radioactivity : None